i think the 1jz is more idiot proof.... i don't think one is more reliable then the other if the owner uses common sense, checkes his oil periodically, uses quality parts and maintains the car well...
performance wise i don't think one is better then the other.... people can argue the 1jz revs more making more top end hp or the 7m has more low end torque but in the end the differences are more or less negligable when it comes to performance i would say. i guess it's up to you. personally i prefer the 7M.
if you have $4500 and you're going to pay this guy every penny you have to do the 1jz swap and think your problems will be over, think again. these cars need constant maintenance.... honestly... figure you'll spend whatever getting the engine repaired.... then add $3000 maintenence for the first yr, $2000 for the second, and $500/yr for all the following years.... if you end up spending less consider yourself lucky, but make sure you prepare yourself to spend more money in the future if you want to keep the car running properly... otherwise a $200 repair ends up being a $2000 repair and things can get way out of hand very quickly if you neglect it.